I have little patience for just about anything. It's that one thing that's a constant on my prayer list for myself. Yes, I've even said, "Lord, please give me patience and give it to me RIGHT NOW!" So I have to admit that I have quit endeavors because it just takes too long to master... or even reach a point of "so-so"ness.
I used to work at a university that offered free tuition to its employees. I used that wonderful benefit to earn my graduate degree and I often encouraged my employees to further their education. Almost every time, the employee balked at the idea of going to school part time for two or five or ten years because that would be too long of time to devote. My response was always, "the time is going to pass anyway, why not use it to gain something that can never be taken away?"
So, when you are facing a long-term challenge - earning a degree, mastering a skill, losing weight, or whatever - just put one foot in front of the other and take one day at a time. It won't make the time go any faster, but neither will quitting.